Instruct Copilot on using raco cover (#671)

Author: jackfirth

.github/copilot-instructions.md

@@ -1,10 +1,14 @@
+# Overview
+
 This repository is a Racket package called Resyntax, which is a refactoring and
 static analysis tool for Racket code. It analyzes code using "refactoring
 rules" written in a domain-specific sublanguage of Racket and implemented using
 Racket's macro system. Resyntax then uses these rules to suggest ways people
 can improve their Racket code. See the [Resyntax documentation][1] and
 [Racket website][2] for more information.
 
+## Adding New Refactoring Rules
+
 When trying to add a new refactoring rule to Resyntax's default
 recommendations, pay special attention to the sections in the Resyntax
 documentation on [what makes a good refactoring rule][3] and on
@@ -16,16 +20,43 @@ how to run it. Beware that Resyntax is *not* a `raco` command. Run it
 using `resyntax fix` or `resyntax analyze`, not `raco resyntax fix` or
 `raco resyntax analyze`.
 
-When creating a pull request, avoid being overly verbose in the pull
-request description. Keep descriptions to a single paragraph. If you need to
-include example code, limit it to one or two small blocks. Do not write
-lengthy, detailed explanations or documentation in the PR description.
-
 If you want to experiment with new refactoring rules you've created, consider
 doing so by cloning the [DrRacket][6], [Herbie][7], or [Typed Racket][8]
 repositories and running Resyntax on them. These repositories contain a lot
 of Racket code and are good candidates for testing new refactoring rules.
 
+## Pull Request Style Conventions
+
+When creating a pull request, avoid being overly verbose in the pull
+request description. Keep descriptions to a single paragraph. If you need to
+include example code, limit it to one or two small blocks. Do not write
+lengthy, detailed explanations or documentation in the PR description. Avoid
+mentioning things that are obvious from the code changes themselves, such as
+lists of files changed. Reserve the PR description for only the most essential
+information, and err on the side of omission. There is nothing wrong with a
+pull request description that is just a single sentence and a mention of what
+issue number is being addressed.
+
+## Code Coverage
+
+When writing tests, you can use the [`raco cover`][9] command to check the
+code coverage of your test cases. The command `raco cover path/to/file.rkt`
+will generate an HTML report showing what code is covered by running the
+indicated files. To check coverage for the whole repository, you can run
+this command:
+
+```bash
+raco cover --suppress-log-execution --package resyntax
+```
+
+The `--suppress-log-execution` flag is necessary to avoid a bug in `raco cover`
+related to Racket's logging system. The `raco cover` tool has a few other sharp
+edges like this; see its documentation for more details.
+
+Pull requests should aim for high code coverage, and an integration with Coveralls
+is set up to help track coverage over time. You can view the Coveralls report for
+the entire repository at [this link][10].
+
 [1]: https://docs.racket-lang.org/resyntax/
 [2]: https://racket-lang.org/
 [3]: https://docs.racket-lang.org/resyntax/Refactoring_Rules_and_Suites.html#%28part._.What_.Makes_a_.Good_.Refactoring_.Rule_%29
@@ -34,3 +65,5 @@ of Racket code and are good candidates for testing new refactoring rules.
 [6]: https://github.com/racket/drracket
 [7]: https://github.com/herbie-fp/herbie
 [8]: https://github.com/racket/typed-racket
+[9]: https://docs.racket-lang.org/cover/
+[10]: https://coveralls.io/github/jackfirth/resyntax

.github/workflows/copilot-setup-steps.yml

@@ -23,4 +23,5 @@ jobs:
       - uses: Bogdanp/[email protected]
         with:
           version: stable
+      - run: raco pkg install --batch --auto cover
       - run: raco pkg install --batch --auto --link --name resyntax